Embodiments of the disclosed technology relates to a thin film transistor liquid crystal display panel and a color filter substrate.
Thin Film Transistor Liquid Crystal Display (TFT-LCD) panels are generally used for manufacturing small-sized or medium-sized liquid crystal displays due to their excellent color property, small thickness and light weight.
In order to improve image quality of the TFT-LCDs, Advanced-Super Dimensional Switching (AD-SDS) technology and In-Plane Switching (IPS) technology are proposed. As for the AD-SDS technology, a multiple dimensional electric field is formed by a horizontal electric field generated between edges of pixel electrodes in the same plane and a vertical electric field generated between the pixel electrodes and counter electrodes. With such a multiple dimensional electric filed, liquid crystal molecules with various orientations, which are located between the pixel electrodes within a liquid crystal cell, just above the electrodes and above the liquid crystal cell, can be rotated. Therefore, operating efficiency of in-plane orientation liquid crystal is enhanced and the light transmittance is increased. The TFT-LCDs manufactured by AD-SDS and IPS technologies have advantages such as wide viewing angle, high aperture ratio, short response time, absence of push mura, and etc.
However, due to the manufacturing processes, formation of electric field and deflection mode of the liquid crystal, the AD-SDS mode TFT-LCDs and IPS mode TFT-LCDs are not formed with a conductive layer on a front surface of a color filter substrate (the surface facing the liquid crystal layer). In this case, electric charges are easily accumulated on the color filter, and thus protection capability of the AD-SDS mode TFT-LCDs and the IPS mode TFT-LCDs is weaken. The color filter substrate comprises a base substrate and a color filter film attached on a front surface of the base substrate, and the color filter film comprises a black matrix and a trichromatic color layer (may further comprises a protection layer).
In order to protect the AD-SDS mode TFT-LCDs and the IPS mode TFT-LCDs from electrostatic damage, the following methods are usually used for performing Electro-Static discharge (ESD) protection in the prior art.
First Method
An Indium Tin Oxides (ITO) layer is deposited on a back surface (opposite to the surface facing to the liquid crystal layer) of the base substrate as a conductive layer and is grounded, so that the charges (from outside or generated by friction) on the color filter are discharged.
However, with this method, new device is needed for the ITO deposition which can not be performed by the existing devices, which leads to a higher cost; the liquid crystal cell is subject to being split during the deposition process, which decreases the production yield; and an additional bonding process with a conductive tape is needed for grounding the ITO layer, which makes the manufacturing process much complex.
Second Method
The black matrix is formed of a metal of Chromium (Cr) on the color filter and is grounded, so that the electric charges (from outside or generated by friction) on the color filter are discharged.
However, a complex process comprising coating film, exposing and developing, etching, lifting-off steps, etc. is needed for forming the black matrix, which leads to higher material and process costs.
Therefore, in terms of the ESD protection for TFT-LCD, the existing AD-SDS and IPS technology have disadvantages such as complicated processes and high cost.